Comparison of DMA-based dynamic data of HTPB-IPDI-bonded high explosive formulation and its binder alone

The dynamic behavior determined by dynamic mechanical analysis (DMA) in torsion mode, of a high explosive charge (HE-charge) formulation called HX522 (HTPB-IPDI binder with 85 mass-% HMX and 6.0 mass-% plasticizer DOA) is compared with its binder alone, called BV_HX522. The HE-charge was used in a Variable velocity HEmispherical Projectile Impact Test (VHEPIT) reported earlier. This is a modified version of the so-called ‘Steven Impact Test’ (SIT) or ‘Steven Projectile Impact Test’ (SPIT). The DMA was operated in the linear visco-elastic range with regard to applied maximum strains. The deformation frequency range was from 0.1 Hz to 30 Hz with HX522 and from 0.1 Hz to 10 Hz with BV_HX522. Data characterizations and evaluations are performed by the shift of maximum temperatures of the loss factor with deformation frequency and with establishing of master curves via the Time-Temperature-Superposition (TTS) or FTS (Frequency Temperature Superposition) procedure. The parameterization of the shifts of the main maximum of the loss factor with deformation frequency, representing the glass-to-rubber transition (GRT), is made with standard and modified Arrhenius equation. For comparison, also the Williams-Landel-Ferry (WLF) parameters are calculated with modified Arrhenius equation. The characterization with master curves comprises appraising valid ranges with the use of so-called ‘van Gurp-Palmen’ (vGP) plots. For establishing the master curves, two optimization ways of the shifts have been applied: (1) using storage shear modulus G’ and (2) using loss shear modulus G". For HX522 both ways are nearly congruent, with BV-HX522 the latter seems more reasonable.